Thermostatic coil



(model.) V

H. W. AXFORD.

THERMOSTA'TIG COIL. UNO. 252,069. Patented Jan. 10,1882.l

WITNESSES. INv-NTOR.

4 use of hot water to suit theposition of any cir- UNTED STAT-Es PATENT OFFICE. n

HARRIS W. AXFORD, OF CHICAGO, ILLINOIS.

THERMOSTATIC COIL.

SPECIFICATION forming part of Letters Patent No. 252,069, dated January 10, 1882. Application tiled January 20, 1881. (Model.)

To all whom it may concern Be it known that I, HARRIS W. AXFoRD, of Chicago in the county of Cook and State of Illinois,i1ave invented a new and useful Improvement in Thermostats for Incubators, of which the followingisa specitication,reference being had to the accompanying drawing, illustrating the improvement, in which the figure is a perspective view.

The nature ofthe present invention consists of a compound coil made of bard rubber and metal riveted together, and then bent, after softenin g the rubber, so as to stay in a desired form when it is cool. This coil differs from coils of two metals, inasmuch as the steel is rst bent and then tempered, and the brass orother metal which is to expand more or less than the steel is also coiled to correspond with the steel coil, after which the two platesfare riveted together; whereas in my thermostat the steel is taken fromflat sheets of commercial steel plate and is held in .a coiled form (except so muchas it may set by the bending process) by the rubber; further, in the fact that' the coils, after being formed, can be contracted or enlarged by the cuit-closer in the incubator.v

In making my thermostat I take a piece of spring-steel one-halt' inch wide, No. 22, and about twelve and three-eighths inches long, and a strip of hard rubber the same width, twelve inches long and one-sixteenth inch thick, and rivet them together at intervals of' about one inch, and bend the surplus length (threeeighths of an inch) of the metal outward to come in contact with a pivot and make the connection. The two plates are then subjected to a heat of boiling water or steam for a minute or two till the rubber is soft.` The two plates are then coiled by the ordinary means, and the rubber becomes set so soon as cooled, so that it will be more efcient, soft, and sensitive where the temperature does not much exceed that necessary for incubating eggs.

A represents the steel plate, and B the rubber plate, which, after being bent as stated, is securedto a post, C, so that by the expansion of'the coils the end D ofthe spring may come in contact with the point E and make connection in the ordinary manner. The bent end D is, however, only a matter of convenience, as it is only necessary that the steel come in contact with the point E.

An important advantage in the manufacture of my thermostats is that they can be made at less cost than where coiled steel-sprin gs are employed, inasmuch as flat spring-steel plates can be cut in strips and combined with the rubber, as stated, by an ordinary mechanic, and double spring-coils can be made to suit any sized oven at no extra cost of tools without the delay and eXtra cost ot' obtaining steel springs which are coiled. Further than this, coils may be enlarged-or contracted to suit any circuitcloser, which is not the case with thermostatcoils now obtainable in the market.

I claim and desire to secure byLetters Pat- 'vent- A thermostatic coil composed of a plate of hard rubber and a plate of spring-steel, the

hard-rubber being bent so as to hold the springsteel in a coiled form, that it may constantly tend to enlarge the coil and give increased sensitiveness to the thermostat, as and for the purpose specified. l i

HARRIS W. AXEORD. 

